>>Not in my area. It is just a regular traffic camera. Emergency
>>sensors are much smaller where I live (about the size of the knob
atop >>the light).
>>Apparently RH has indicated that it is a traffic sensor to change the
>>light when a vehicle is present. I thought they buried those sensors.
>No, he's talking about a special sensor on top of the light support,
>that responds to a certain frequency of strobe light, and literally
>changes the light on demand. It's used by emergency vehicles (police,
>fire, ambulance)so they can get through the gridlock. The system has
>some snazzy 21st century name, but I can't remember what it is.
>If you determined the freq, you could make one, but I'd be awfully
>skittish about using it; I'm sure it'd be quite illegal.
>But these aren't those - I don't even think they're ticket-cams - just
>surveillance, like that other poster said, probably in a parking lot.
3M Opticom, and Tomar Strobecom are the big two in light controls. They
operate on the same principle though. They use a set frequency strobe
to trigger the light.
10Hz for low priority: Increases your green light time.
14Hz for high priority: Turns your light green and all others red plus a
few other items.